Self-indicating refillable electric cartridge fuse



July 5, 1932. 3, SQHMID 1,366,491

SELF INDICATING REFILLABLE ELECTRIC CARTRIDGE FUSE Filed Aug. 29, 1929a2 i 2/ 9 m m. 7 26 y; E 35 25 25 V 2% 7.44. 2/ /9 20 f .3. 2 d m1! 33/5 A? 25 LI /.6 W M /2 23 30 X i9( 7 /2 25 I JZ L gig.

255M415 w fiww INVENTOR ATTORNEY WESS S BY Patented July 7 5, 1932UNITED STATES PAT NT OFFICE r ANcIs CHARLES SCHMID, OF THE UNITED STATESNAVY sELE-mnIcATm EEF LLABLE ELECTRIC CARTRIDGE FUSE Application flledmigust 29.1929. Serial No. 389,259.

when such fuses havebeen of'the self indicat ing type it has beennecessary to use particular care in installing the fuseso that theindicator will be visibleat the front of the panel board.

Certain types of fuses have beenheretofore I features wherebytheelectrician could determine the particular fuse that has blown, but suchfuses have been more expensive than those of the blind type, and whenblown have included no provision for being re- I filled, thefuse being.discarded and replaced with anew one at additional expense. To

solder the broken ends of a'fusible link has heretofore been impossiblewith certain types of fuses, and impracticablewith others by reason ofthe time required, for suchpurpose.

Heretofore, when fusesfhave included'provision'for replacement of thefusible element they have always been of the blind type, having thedisadvantage above referred to. The primary object of my invention is toenable the fuseto be constructed so that it will'be self indicatingandalsoso' that the fusible link element will be replaceable with a newfusible element whenever it has been destroyed, so that the samecart-ridgecan be used over'and overagain, and also to enable the fuse tobe constructed so'that when the fuse has blown, the indicator or flagwill. be visible in any position of the fuse, whereby the installer canquickly positionthe fuse between the contacts without taking time tofind the indicator side and position said side at the'front. l

A further object is to provide a fusible element or link which can bekept on hand in quantities for replacement purposes. Still furtherobjects are to simplify and improve the construction of electriccartridge fuses, to reduce the cost ofmanufacture of the fuse as awhole, as well as the cost of replacement, and to provide an electriccartridge fuse which will be self indicating and refillable and as well,quick acting and arcless.

Other objects and advantages of the invention will be hereinafterspecifically pointed out, orwill become apparent, as thespecificationproceeds. i

-VVith the above indicated objects in view, the invention resides incertain novel 'constructions and combinations and arrangement of parts,clearly described in the following specification and fully illustratedin the accompanying drawing, which shows an embodiment of the inventionas at present preferred. f

In the drawing:

Fig. l is a perspective view of the fuse bodyi Fig. 2 is a. longitudinalsectionalview 30 through the fuse,-showing the parts in operatingposition. i 1

' Fig; 3 is a partial sectional view taken on the lne 3-3 of Fig. 2. v

.Fig. 4 is a partial longitudinal sectional view similar to Fig. 2,showing the parts in the position assumed when the fusible element hasblown and the indicator or flag hence caused to assume) its indicatingposi- 9 tion. 0

Fig. 5 is a perspective view of the refiller plate.

Fig. 6 is a perspective view of the renewable fusible link.

The electriccartridge fuse 10 in this ing5 stance includes a cylindricalshell or body 11, preferably formed of insulating material, and having ahomer chamber 12. A cylindrical head 13 is secured at one end of theshell. "This head 13 has asmaller diameter screw-threaded portion 14 andis provided with an axial aperture 15 communicating with the innerchamber 12. The interior walls of the head 13 are inclined at oppositesides, as seen at 16 and 17 so that they converge from the end ofchamber 12 toward the axial aperture 15.

At the opposite end of the shell 11' a rim 18 is provided; and acylindrical housing 19, having a chamber 20, is adapted to be removablysecured to the end rim 18 by means of one or more bayonet joints as seenat 21, though any other approved form of securing means may be used forthe latter. The housing 19 and rim 18 are formed of conducting materialsuch as brass or copper.

Within the housing chamber 20 I provide an indicator device which inthis instance is in the form of a disk 21 including an annular flangeand having an attaching device, such as a hook 22, secured at thecentral portion of the disk and arranged to extend in the direction ofthe shell chamber 12. Resilient means, such for instance as acompressible spring 23, are provided between the indicator disk 21 andthe rim 18 for the shell or body 11.

A suitable fusible element is adapted to be secured to the indicatordisk 21, and in this instance I provide an elongated link 24, formed ofsuitable fusible material. This link 24 has a reduced portion or neck 25about midway of its length, though the latter may be provided at anydesired point, and securing means in the form of an aperture 26 at oneof its ends. The hook 22 is adapted to be passed through the aperture 26to hold this end of the fuse in position.

The fuse link 24 being attached at one of its ends as described, thehousing 19 is placed over the end of the shell 11 and secured in placeat the bayonet joint 21, the free end of the fuse link extending throughthe chamber 12 and aperture 15. During this passage the fuse link isguided into and past the aperture 15 by the inclined wall portions 16and 17. The fuse link is drawn outward, compressing the spring 23 towhich the opposite end of the fuse link is secured, and bringing thespring 23 into contact'with themetallic rim 18, to cooperate with thehook 22 in establishing electrical connection between the housing 19 andfusible link 24. The spring 23 may be compressed part way, as seen inFig. 2 and electrical connection will still exist because the base ofthe spring engages the rim 18. The outer, free end of the fusible linkis adapted to be held in place at the outer end of the head 13 byaremovable securing or refiller plate 28 havingan-inwardly extending lug29 adapted to engage the link 24 with a wedging action in the axialaperture 15. The free end 30 of the fusible link is then bent over theouter surface of the refiller plate 28 as seen in Fig. 3, after which acylindrical cap 31 is screwed on to the threaded portion 14 of the head13 so that the inner face of the cap securely clamps the end of thefusible link against the refiller plate. In this position of the parts,electrical connection is established between the fusible link, the cap31 and head 13, and the fuse is ready for use. The cap 31 preferably hasa slot 32 for use in applying a screw driver to tighten the cap 31.

Overload of electric current in the circuit will cause the fusible linkto melt at its weakest point, 25, and this parting of the link willcause the spring 23 to be released, breaking the electric circuit.Expansion of this spring forces the indicator disk or flag 21 from itsnormally concealed position to its outer limit against the outer end ofthe housing chamber 20, as seen at 33 in Fig. 4. A plurality of windowopenings 34, 35 and 36 are provided through the side walls of thehousing 19 so that when the circuit has been broken and the indicator orflag forced outward as just described, the flange of the flag, which isindicated by the reference numeral 27 will be visible through thewindows 34, 35 and 36. These windows are located at spaced points aroundthe wall of the housing 19 so that at least one of the windows will belocated toward the front regardless of the axial position of the fusewhen placed in position between its respective contacts on the panelboard.

To refill the cartridge and enable the same to be used over again, thecap 31, refiller plate 28, and housing 19 are disassembled, as will bereadily understood, and the separated ends of the fusible link withdrawnfrom the shell 11. The end of the fusible link connected to the hook 22is then withdrawn and a new fusible link of the same construction, asseen in Fig. 6, is attached to the hook 22 and the parts are reassembledas hereinabove described.

It will be understood that the fusible link 24 may be constructed ofwire or other equivalents as well as of thin leaf metal as shown herein.

My present invention provides a fuse which is self-indicating,refillable, and as well, areless, because the construction enables thebroken ends of the fusible link to be instantly separated through theaction of the compressible spring. The fuse thus presents in asimplified unit, the combined advantages of practically all types ofelectric cartridge fuses. It can be rated for any voltage or amperage;and it operates and indicates instantly. When it is desired to renew thefusible element the aid of a screw driver is all that is required. Therefills can be furnished in quantities for each fuse, at a triflingexpense, so that fuses once purchased can be maintained in operatingcondition by being refilled whenever necessary at an expense that ispractically insignificant. The present imuse and economy in cost andupkeep.

The hereinbefore" described construction admits of considerablemodification without departing from the. invention; therefore, I

do not wish to be limited to the'precise arrangements shown and stepsdescribed, which are, as aforesaid, by way of illustration mere 1y. Inother words, the scope of protection contemplated is to be taken solelyfrom the appended claims, interpreted as broadly as is consistent withthe prior art.

What I claim as new, is: I

1. An electric cartridge fuse comprising a shell, a head secured atoneend of said shell, said head. having an, axialaperture, a housing at theopposite end of said fuse, an indicator disk positioned in said housing,resilient means interposed betweensaid'indicator and the end ofsaidshell, a replaceable fusible link having one of its endsattached to saidindicator, the opposite end of said link adapted to extend through saidaxial aperture at the opposite end of the shell, means to hold the endof said fusible link in wedging engagementat said axial aperture, ascrew cap on said cyindrical head, said cylindrical housing having aplurality of spaced window openings at the outer sides thereof, wherebythe breaking of said fusible link is adapted to'release said resilientmeans and project said indicator outward toward the outer end of saidhousing and render I said indicator disk visible through said windowopenings.

2. An electric cartridge fuse comprising a shell. a head securedat oneend of said shell, said head having an axial aperture, the interiorwalls of said head having inclined sides converging toward said axialaperture,ahousing removably mounted at the opposite end of said fuse, anindicator'disk positioned in said housing, a compressible spring betweensaid indicator and the endof said shell, an elongated replaceablefusible link having one threaded on said cylindrical head to secure theextended end of said fusible link in clamping engagement, saidcylindrical housing having a plurality of spaced Window openings at theouter sides thereof, whereby the breaking of said fusible link isadapted to release said spring and project said indicator outward towardthe outer end of said housing and render the edge of said indicator diskvisible through said window openings.

3. In an electric cartridge fuse, a hollow cylindrical body, a rimsurrounding one end of said body, a housing for said end and beingprovided with bayonet slots, pins extending from said rim and receivingsaid bayonet slots for securing the housing to said body, said housinghaving openings arranged in annular formation about the same, a springpressed indicator in the form of a disk including an annular flangeadapted to show through the openings and mounted for slidable engagementwith the housing, a head for the opposite end of said body, areplaceable fusible element disposed in said body, a hook secured to thedisk and detachably receiving one end of said fusible element forconnecting the latter to the disk, a cap for said head, means receivedby said head and cooperating with said cap for securing the opposite endof the fusible element to said head, and said fusible element normallyholding said disk with its annular flange out of registration with theopenings.

In testimony whereof I have aflixed my signature.

FRANCIS CHARLES SCHMID.

of its ends removably attached to said indi-v

